My choice too. Also great:
Marge: We’re too late!
Cobb: I shouldn’t have stopped for that haircut. Sorry
Quimby: And let me say ‘May the force be with you.’
Leonard Nimoy: Do you even know who I am?
Quimby: I think I do. Weren’t you one of the Little Rascals.
Homer: Are we gonna die?
Bart: Yeah. But at least we’ll take a lot of innocent people with us.
I also vote for this one! It’s my absolutely all time favourite.
I’ve always loved Boy Scoutz N The Hood. So many quotes, and just the right note of surreality.
Homer: Awww, twenty dollars! I wanted a peanut!
Homer’s Brain: Twenty dollars can buy many peanuts.
Homer: Explain how.
Homer’s Brain: Money can be exchanged for good and services.
Homer: Woo hoo!
Barney: I don’t know where you magic pixies came from, but I sure do like your pixie drink!
Bart: [examining a knife safety guide] ‘Don’t Do What Donny Don’t Does.’ They could have made this clearer.
Marge: Homie, I’m going to the store. What would you like for dinner?
Homer: [happily] Steak?
Marge: Money’s too tight for steak.
Homer: [happily] Steak?
Marge: worried Marge noise…all right, steak.
Homer: Marge, don’t discourage the boy. Weaseling out of things is important to learn. It’s what separates us from the animals! …Except the weasels.
Homer: Ooh, floor pie!
Homer: How was jerk practice, boy? Did they teach you how to sing to trees? And build crappy furniture out of useless wooden logs? [his chair collapses] D’oh! Stupid poetic justice.
Bart: Actually, we were just planning the father-son rafting trip.
Homer: Heh heh…you don’t have a son.
Homer: See that, boy? Your old man was right, not Flanders. We are doomed! In your face, Flanders!
Flanders: God speed, little doodle.
Homer the Great is probably the one that makes me laugh the most… “Attach the Stone of Triumph!”. That’s the one that first got me hooked on the Simpsons.
But I think my personal favorite is 'Round Midnight, the one where Bleeding Gums Murphy dies. I always like the Lisa episodes, and this episode has my favorite ending of all.
You Only Move Twice if I had to pick only one.
But Homer vs. the 18th Amendment came in a rrreeeeaaaaaalllllll close second. Damn you for making me choose.
It’s interesting you bring this up. I think the thing is, usually Homer is faced with the realization that he needs Marge after he’s in the doghouse for doing something incredibly insensitive or inconsiderate. In this episode, he really is innocent of any wrongdoing, so the discovery of his soulmate isn’t motivated by his desire to get back in her good graces, but by his genuine quest for that perfect somebody. Homer and Apu came a close second, but I really am crazy about this ep.
Who loves short shorts?
WE LOVE SHORT SHORTS!
Oh, man, so many great episodes chosen already. But I want to put in a mention of Sweet Seymour Skinner’s Baadasssss Song, because that one has the greatest sight gag of all time: the “K” falling to earth in the background. And I love the ending.
“Teach me”
I’m going to be crazy and pick something from the 11th season: E-I-E-I-(Annoyed Grunt), or the Tomacco episode.
This starts with the Poke of Zorro movie, includes the awesome B-52s glove-slap montage, and just has so many great scenes
Homer: Dueling at dawn. How did it ever come to this?
Lisa: [hanging up phone] The national weather service says dawn
is still scheduled for 6:20 tomorrow and to please stop
calling.
At Sneed’s Feed and Seed (where Homer eventually buys gummi bears)
Farmer 1: Well, well. Look at the city slicker pulling up in
his fancy German car.
Homer: This car was made in Guatemala.
Farmer 2: Well, pardon us, Mr. Gucci loafers.
Homer: I bought these shoes from a hobo.
Farmer 1: Well la-de-da, Mr. Park Avenue manicure.
Homer: I’m sorry, I believe in good grooming.
Ralph: [takes a bite of a tomacco, but spits it out] Oh, Daddy,
this tastes like grandma.
Wiggum: [takes a bite, and likewise spits] Holy Moses, it does
taste like grandma!
Ralph: I want more.
Wiggum: Yeah, me too. We’ll take a bushel or a pack or just –
just give it to me.
I also love the tractor gag.
What? No love for “Simpsoncalifragilisticexpiala(Annoyed Grunt)cious” (the Mary Poppins parody ep)? I love that episode! It’s got:
• terrific songs with great lyrics (“don’t pout, don’t sob, just do a half-assed job!”)
• Burns getting struck by lightning
• Willy’s line: “Then she got her eyesight back. Suddenly the ugliest man in Glasgow wasn’t good enough for her!”
• Marge demonstrating the strength of her hair by holding up a beach umbrella with it
• Sherry Bobbins and Barney boozing up and singing “Margaritaville”
• The end of the episode (Sherry meets the airplane engine)
And so much more!
Really folks, you gotta love that one.
I love this one too. It’s not my favorite, but I just wanted to offer my support against all the Tomacco haters. 
Lots of great episodes in this thread, but I thought I’d throw out the as-yet-unmentioned Mr. Plow.
I’m Mr. Plow, that’s my name,
that name again is Mr. Plow!
I’m Mr. Plow, and I’m here to say
I’m the plowin’-est guy in the USA
I got a big plow and I move a lot of things
like your cow if you have one!
That is my favorite skit from a Treehouse of Horrors episode. I would have listed it as my favorite episode but since it’s not a whole episode I didn’t.
I’ve finally made a decision- my favorite episode depends on what mood I’m in. Right now, I’m gonna say “Marge vs. the Monorail”- if Conan O’Brian never had gotten a talk show, he still would have made his place in history for writing this episode alone. And it has what is possibly the best Homer-not-realizing-what’s-going-on moment in the series’s history (as well as one of Matt Groening’s favorite lines of all time):
“There’s a family of possums living in the engine!”
“I call the big one Bitey.”
The names on those products are just great- especially “Ham Ahoy!” (I love the picture of the sea-captain pig on the package) and best of all, “TUBBB!”
That’s your solution to everything- to move under the sea. It’s not gonna happen!
New Kids on the Bleech where Bart, Milhouse Ralph, and Nelson form boyband PARTY POSSE and NSync comes by and even in real life they move in choreographed dance moves.
and the whole thing is set up by the navy and he watches the kids and fantasizes about them enlisting “thats right…protect the country…” its amazing.
“those wack invertebrates will sting you…OLD SCHOOL”
So many great memories… sniff
Many of my all time faves have been mentioned, but one still missing is Burns Verkaufen Der Kraftwerk, where Mr. Burns sells the plant to a pair of Germans.
They conduct a personnel review of everyone at the plant, and Homer’s interview goes like this:
German: You have been safety inspector for two years. What initiatives have you spearheaded in that time?
Homer: Uh… All of them?
German (exchanges a look with the other German): I see. … Then you must have some good ideas for the future as well?
Homer: I sure do!
[long awkward silence]
German: Such as…?
Then after Homer suggests the vending machines should be less picky with crumped dollar bills since “a lot of employees really like candy”, the Germans launch him into a wonderful dream sequence by saying “We understand… We Germans are from the Land of Chocolate.” (*Mmmm… The Land of Chocolate…*)
Best of all, the systematic Germans subsequently say over the plant PA that “we regret to announce the following layoffs, which I will read in alphabetical order. Simpson, Homer. That is all.”
…Right after Lenny and Carl comment on how “those Germans aren’t so bad… Sure they’ve made a few mistakes in the past, but aah, that’s why pencils have erasers!”
I have to go with Behind the Laughter, the mockup of VH-1’s *Behind the Music * series.
Highlights include:
Homer: I’d like to set the record straight. I thought the cop was a prostitute."
Jimmy Carter (rapping): I got a brother named Billy. And my teeth look silly. Break it down"
I also loved “Cheezus & Rice” and “Uncle John’s Country Fillin’ - Just squeeze and serve!”
The parody of The Shining, by far. Every line is quotable and pure gold.
To this day, whenever anything creepy happens I can’t help but say “Hmmm, the blood usually gets off on the 2nd floor…”
I’ll go for The City of New York vs. Homer Simpson. Highlights:
The flashback of the first time Homer visited New York, with the policeman stealing his camera, being chased by a pimp, etc.
The immigrant street vendor
Homer yelling “jump in the car, no time for the baby” as he drives alongside the rest of his family in a carriage
Since this one has been mentioned, I’ll choose another family themed favourite of mine where Homer ate the hallucinogenic hot pepper and, with the help of his spirit guide, rediscovered his love for Marge.